Improvement in brake-shoes



.|. W. MUFFITT.

Brake Shoes.

N0. 138,514. v Patented May 6,1873.

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NI'IED STATES PATENT OFFICE.

JOHN W. MOFFITT, OF HARRISBURG, PENNSYLVANIA.

' IMPROVEMENT IN BRAKE-SHOES.

Specification forming part of Letters Patent No. 138,514, dated May 6,1873; application filed March 19, 1873.

To all whom it may concern:

Be it known that I, JOHN W. MOFFITT, of Harrisburg, county of Dauphinand State of Pennsylvania, have invented an Improved Brake-Shoe, ofwhich the following is a specification:

'and spacing the interlocking abutments or parts, so that theintermediate spaces may allow the shoe to be removed sidewise from theholder by a limited vertical displacement to avoid hindrances thatrender greater vertical shifting objectionable; third, in the peculiarform of the tenons of the shoe and of the bits or rests in the holder,by the conjoint action of which they are made to hug each other and tobear greater stress, to be noise and snap proof, and can be kept keyedperfectly taut; fourth, in the keying device, consisting of arectangular lock-bar whose outer end or head is two-parted, like aclaw-hammer, and a lug on the shoe-holder, over which the claw-head ispassed and kept in place by a wire tab, through an eye in said lug,outside of said claws. it I In the accompanying drawing making a part ofthis specification, Figure 1 is a side elevation of my improved shoe, inwhich the shoe and the shoe-holder are represented in position for brakeuse. Fig. 2 is'a side elevation of my invention, showing the keyingdevice removed and the shoe vertically shifted from its seat in theholder sufficiently to allow it to be detached sidewise.

Similar parts are similarly marked in the following general description.

K is the shoe. AB are the tenons thereon. W is the shoe holder or block.N M are its carriers or attachments for the brake-bar. P P are the tenonsockets, pockets, or mortises in the shoe-holder frontlets. a s are therests or bits between the frontlet-cheeks. R is the lock-bar of thekeying device. T is the rear lug on the holder W, in which a wire tabstops the lock-bar to keep it from undoing. The shoe K is in form a tiresegment, slightly rounded on its back or rear side, and its matrix inthe frontlets of the holder is slightly hollow or dished vertically. Onits oval side are formed the double-hooked tenons A B on its verticalmiddle, equidistant from its transverse middle. The teuons A B are madesimilar, each being an oval hook, 0 on its inner side and an angularhook, s, on its outer side. Both hooks of the teuon are extended by asharp pitch to the limit of the tenon-crown a b so that the hook-crownis truncate vertically but flat transversely, and the angle .9 and thecurve 0 are made to cut the tenon-body, relatively or exchangeably, soas to economize its strength. The angle of the hook s is less than aright angle, so that stress on the shoe may tend to bind the tireagainst the holder-frontlets when the hook is hooked on the bit .9, andthe correlative curved hook 0 of the other teuon is kept securely on therest a by the conjoint act of the lock-bar D on the adjacent straightside of the tenon, and by the pitch of said straight side, and by thecurve of the rest or bit n. The holder or block W is made to receive theshoe into and against the frontlet P above and P below. The frontletsare recessed vertically by parallel-walled pockets wide enough toadmitthe flat-sided tenons snugly. The cheeks of the frontlets aremassed together at the lower ends of the pockets by the oval and angularbits or s, behind which are left openings to allow dust or otherimpediments to drop out of the pockets. The summit of the oval bit a andthe apex of the angular bit 8 are further from the boundary curvebetween the shoe-tire and the frontlet-cheeks than the correspondingsummit and apex of like parts of the tenons are, so that when the forceof gravity or-brake-tension is on the shoe it will be firmly drawnagainst the cheeks of the front-lets, thus rendering it noiseless andsnap-proof. The frontlet-abutments are spaced apart far enough to allowthe tenons free exit sidewise when the shoe is shifted vertically, asshown in Fig. 2. The distance from teuon to tenon is therefore a littlegreater than the vertical measure of the frontlet-arch to facili tatesaid sidewise displacement.

The sidewise detachment of the shoe from the holder is thus effected bycomparatively little vertical shifting, thus avoiding the objectionsurged against shoes in which greater throw is required, and consequentlymore hindrances are encountered. Moreover, the form of the tenons andthe corresponding bits is such that the shoe may be inverted should oneend of the tire wear more rapidly than the other. Thus its whole extentmay be utilized. Besides, it can be applied alternately on. oppositesides of the truck, so that both sides of the face of the tire may beutilized.

The incisions in the tenons to form the hooks on the shoe are madealternately, so that the dent of the angle and the cut of the curve maynot bite the tenon-body oppositely,thus economizin g all the availablestrength of the body, and consequently avoiding the grave objectionsurged against oppositely-cut dovetails.

I do not limit my improvement to the couple of an angle and a curve, ascouples of two angles, or two sharp curves, may be employed in themanner shown, the principle being in either case to bite the tenon-bodyalternately, not oppositely.

The keying device consists of the rectangular lock-barD, fitting into asurplus rectangular cavity above the tenon edge as when in place in theupper frontlet-abutment, as shown in Fig. 1. The outer end of thelock-bar is turned-uplip form to hold by in removing it, and has thelower part of its head divided, claw-hammer form, with the curve of theclaw reversed to receive a wire tab, which is passed through an eye in alug, T, after the lock-bar is entered to its place. The claws bestridesaid lug in entering the lock-bar to its place, and, when in place, thewire tab is passed snugly through said lug against said claws. The wiretab checks the jumps or jostle of the lock-bar, and

the lock-bar checks the reaction or concussion of the shoe in the act ofbraking.

It will be observed also that my improvement is very compact orclose-hitched, and especially adapted for air-brakes, in which as littlelost motion as possible is desired to prevent much throw or stroke ofthe piston mechanism.

Should my device be deemed too solid, a layer of rubber can be insertedbetween the holder-frame W and the brake-bar when they are boltedtogether.

I claim- 1. The shoe K, having the two similarlyformed double-hookedtenons A B, in combination with the bits n s in the holder W, in-

terlocking vertically, the shoe being reversible, substantially in themanner as and for the purpose herein set forth.

2. The arrangement of the holder-abutments P P, in relation to thetenons A B, to effect the sidewise detachment of the shoe from theholder by a limited vertical displacement, substantially as herein setforth.

3. The tenon, having the notch s and the cut 0 thereon, as and for thepurpose herein set forth.

4. The keying or locking device, composed of the bar 1), lug T, wire tabor its equivalent,

arranged in the upper abutment, in the manher as and for the purposespecified.

JOHN W. MOFFITT.

Witnesses:

THEOPHILUS WEAVER, D. A. KEPNER.

